Pre beta 1-HDL, a key element of reverse cholesterol transport: its potential as a biomarker

Pre beta 1-HDL is the smallest plasma lipoprotein, consisting of ApoA-I and a small amount of phospholipid and cholesterol. It plays an important role in cholesterol efflux, the first step in reverse cholesterol transport. Pre beta 1-HDL may be a biomarker reflecting cholesterol efflux activity, because pre beta 1-HDL is thought to be the first product when ApoA-I removes cell-derived cholesterol, mediated by ABCA1 on cell membranes. However, pre beta 1-HDL is also formed by alpha-HDL remodeling and triglyceride-rich lipoprotein lipolysis while it is catabolized by the lecithin-cholesterol acyltransferase reaction, suggesting that the plasma pre beta 1-HDL level is influenced by factors involved in those formation and catabolic pathways. In fact, the plasma pre beta 1-HDL level is elevated in coronary artery disease. That elevation may reflect a lipid metabolic disorder that is undetectable by conventional lipid markers. However, it remains unclear what this elevation in the body reflects and what the cause is. We hope that these points will be further elucidated in future studies.